Synthesis of Platinum and Palladium Complexes as Narrow-Band Phosphorescent Emitters for Full Color Displays

ABSTRACT

Platinum and palladium complexes are disclosed that can be useful as narrow band phosphorescent emitters. Also disclosed are methods for preparing and using the platinum and palladium complexes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/479,921, filed May 24, 2012, which claims the benefit of U.S.Application No. 61/490,111, filed May 26, 2011, both of which are herebyincorporated by reference in their entirety.

STATEMENT OF GOVERNMENT SUPPORT

The present invention was made with financial support from the NationalScience Foundation under Career Grant No. 0748867. The U.S. governmenthas certain rights in this invention.

BACKGROUND Technical Field

The present disclosure relates to platinum and palladium complexes thatcan be useful as narrow band phosphorescent emitters in, for example,full color displays.

Technical Background

Compounds capable of absorbing and/or emitting light are ideally suitedfor use in a wide variety of applications, including optical andelectro-optical devices, photo-absorbing devices, and as markers forbio-applications. Much research has been devoted to the discovery andoptimization of organic and organometallic materials for use in suchapplications. Generally, research in this area aims to accomplish anumber of goals, including improvements in absorption and emissionefficiency, as well as improvements in processing ability, among others.

Despite significant advances in research devoted to optical,electro-optical, and marker materials, existing materials have a numberdisadvantages, including poor processing ability, inefficient emissionor absorption, and less than ideal stability, among others. Thus, a needexists for new materials which exhibit improved performance in opticalemitting and absorbing applications. This need and other needs aresatisfied by the present invention.

SUMMARY

The present invention relates to platinum and palladium complexes thatcan be useful as narrow band phosphorescent emitters in, for example,full color displays. Such complexes are useful inorganic-light-emitting-diodes (OLEDs).

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

In one aspect, the present invention provides a complex that can berepresented by the general formula

where (N{circumflex over ( )}C) represents the emitting portion of theligand, (L{circumflex over ( )}X) represents an ancillary portion of theligand, which may be linked, or not linked, M represents platinum orpalladium, R represents a linking motif that connects (N{circumflex over( )}C) to (L{circumflex over ( )}X) while disrupting the conjugationbetween them.

In one aspect, the excited state properties of the complex can berepresented by the scheme:

The energy of the ligand centered triplet state (³LC), and themetal-to-ligand charge transfer state (¹MLCT) can be tunedindependently. The nature of the emitting portion (N{circumflex over( )}C) drive the emission energy, as well as the width of the emissionprofile. The nature of the ancillary portion (L{circumflex over ( )}X)is responsible for the enhancement or suppression of the vibronicprogression in the emission profile, as well as the decay ratesassociated with emission. Control of both can yield complexes that emitnarrowly at wavelengths useful for display applications.

In one aspect, the present invention provides a complex that can berepresented by the formula:

wherein M represents platinum, palladium, or a combination thereof,where each of Ar₁, Ar₂, and Ar₃ independently represent an aromatic ringor heterocyclic group which can be substituted or unsubstituted; whereineach of X₁, X₂ and X₃ can individually be coordinated to a platinumand/or palladium atom, and can independently represent a carbon or anitrogen atom, wherein Ar₅ can represent an aromatic ring, aheterocyclic group, or a combination thereof, wherein Ar₆ can representan aromatic ring, a heterocyclic group, a combination thereof, or can beabsent; wherein W can be coordinated to a platinum or a palladium atom,and can be represented as a halogen atom, an aryl group, or a heteroarylgroup which may be substituted bonded directly or through an oxygenatom, sulfur atom, nitrogen atom, or phosphorous atom; wherein A canrepresent a linking atom, such as, for example, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof, and wherein A canoptionally be substituted, wherein each of b₁, b₂, and b₃ canindividually optionally be present or absent, and if present canindependently represent oxygen, sulfur, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof.

In another aspect, the present invention provides a complex that can berepresented by the formula:

wherein M represents platinum, palladium, or a combination thereof,wherein each of Ar₁, Ar₂, Ar₃, and Ar₄ independently represent anaromatic ring or heterocyclic group which can be substituted orunsubstituted; where each of X₁, X₂, X₃ and X₄ can individually becoordinated to a platinum and/or palladium atom, and can independentlyrepresent a carbon and/or a nitrogen atom, wherein Ar₅ can represent anaromatic ring, a heterocyclic group, or a combination thereof, whereinAr₆ can represent an aromatic ring, a heterocyclic group, a combinationthereof, or can be absent; wherein each of A₁ and A₂ can independentlyrepresent a linking atom, such as, for example, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof, and wherein each of A₁and A₂ can independently optionally be substituted, wherein each of b₁and b₂ can individually optionally be present or absent, and if presentcan independently represent oxygen, sulfur, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof.

In still another aspect, the present invention provides a complex thatcan be represented by the formula:

wherein M represents platinum, palladium, or a combination thereof,wherein each of Ar₁, Ar₂, Ar₃, and Ar₄ independently represent anaromatic ring or heterocyclic group which can be substituted orunsubstituted; wherein each of X₁, X₂, X₃ and X₄ can individually becoordinated to the platinum and/or palladium atom, and can independentlyrepresent a carbon and/or a nitrogen atom, wherein Ar₅ can represent anaromatic ring, a heterocyclic group, or a combination thereof, whereinAr₆ can represent an aromatic ring, a heterocyclic group, a combinationthereof, or can be absent; wherein A₁ can represent a linking atom, suchas, for example, nitrogen, carbon, boron, phosphorus, silicon, or acombination thereof, and wherein A₁ can optionally be substituted,wherein each b₁, b₂, and b₃ can individually optionally be present orabsent, and if present can independently represent oxygen, sulfur,nitrogen, carbon, boron, phosphorus, silicon, or a combination thereof.

Also disclosed are full color display devices comprising one or more ofthe platinum complexes described herein.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated in and constitute apart of this specification, illustrate several aspects and together withthe description serve to explain the principles of the invention.

FIG. 1 illustrates an emission spectra of the compound Pt-N1N (inset) at77K and room temperature, in accordance with various aspects of thepresent disclosure.

FIG. 2 illustrates the room temperature emission spectra of thecompounds Pt-N1N, Pt-N2N, and Pt-N3N(inset), in accordance with variousaspects of the present disclosure.

Additional aspects of the invention will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or can be learned by practice of the invention. Theadvantages of the invention will be realized and attained by means ofthe elements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION

The present invention can be understood more readily by reference to thefollowing detailed description of the invention and the Examplesincluded therein.

Before the present compounds, devices, and/or methods are disclosed anddescribed, it is to be understood that they are not limited to specificsynthetic methods unless otherwise specified, or to particular reagentsunless otherwise specified, as such can, of course, vary. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular aspects only and is not intended to be limiting.Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of the presentinvention, example methods and materials are now described.

The chemical names and structures disclosed herein can also comprisebonds stemming from those structures. For example, if

is pyridine, then the bonds from the

structure are included in the pyridine, thus, for example, X₁ can beeither the nitrogen or a carbon in the pyridine that is bonded toanother component of the complex, for example the M component.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a component”includes mixtures of two or more components.

Ranges can be expressed herein as from “about” one particular value,and/or to “about” another particular value. When such a range isexpressed, another aspect includes from the one particular value and/orto the other particular value. Similarly, when values are expressed asapproximations, by use of the antecedent “about,” it will be understoodthat the particular value forms another aspect. It will be furtherunderstood that the endpoints of each of the ranges are significant bothin relation to the other endpoint, and independently of the otherendpoint. It is also understood that there are a number of valuesdisclosed herein, and that each value is also herein disclosed as“about” that particular value in addition to the value itself. Forexample, if the value “10” is disclosed, then “about 10” is alsodisclosed. It is also understood that each unit between two particularunits are also disclosed. For example, if 10 and 15 are disclosed, then11, 12, 13, and 14 are also disclosed.

As used herein, the terms “optional” or “optionally” means that thesubsequently described event or circumstance can or can not occur, andthat the description includes instances where said event or circumstanceoccurs and instances where it does not.

The term “alkyl” as used herein is a branched or unbranched saturatedhydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl,isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl,dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, and the like. Thealkyl group can be cyclic or acyclic. The alkyl group can be branched orunbranched. The alkyl group can also be substituted or unsubstituted.For example, the alkyl group can be substituted with one or more groupsincluding, but not limited to, optionally substituted alkyl, cycloalkyl,alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, orthiol, as described herein. A “lower alkyl” group is an alkyl groupcontaining from one to six (e.g., from one to four) carbon atoms.

The terms “amine” or “amino” as used herein are represented by theformula NA¹A²A³, where A¹, A², and A³ can be, independently, hydrogen oroptionally substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl,alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

The term “halide” as used herein refers to the halogens fluorine,chlorine, bromine, and iodine.

The term “hydroxyl” as used herein is represented by the formula —OH.

The term “nitro” as used herein is represented by the formula —NO₂.

The term “nitrile” as used herein is represented by the formula —CN.

The term “thiol” as used herein is represented by the formula —SH.

Disclosed are the components to be used to prepare the compositions ofthe invention as well as the compositions themselves to be used withinthe methods disclosed herein. These and other materials are disclosedherein, and it is understood that when combinations, subsets,interactions, groups, etc. of these materials are disclosed that whilespecific reference of each various individual and collectivecombinations and permutation of these compounds can not be explicitlydisclosed, each is specifically contemplated and described herein. Forexample, if a particular compound is disclosed and discussed and anumber of modifications that can be made to a number of moleculesincluding the compounds are discussed, specifically contemplated is eachand every combination and permutation of the compound and themodifications that are possible unless specifically indicated to thecontrary. Thus, if a class of molecules A, B, and C are disclosed aswell as a class of molecules D, E, and F and an example of a combinationmolecule, A-D is disclosed, then even if each is not individuallyrecited each is individually and collectively contemplated meaningcombinations, A-E, A-F, B-D, B-E, B—F, C-D, C-E, and C—F are considereddisclosed. Likewise, any subset or combination of these is alsodisclosed. Thus, for example, the sub-group of A-E, B-F, and C-E wouldbe considered disclosed. This concept applies to all aspects of thisapplication including, but not limited to, steps in methods of makingand using the compositions of the invention. Thus, if there are avariety of additional steps that can be performed it is understood thateach of these additional steps can be performed with any specificembodiment or combination of embodiments of the methods of theinvention.

The term “heterocyclic” or the like terms refer to cyclic structuresincluding a heteroatom. Thus, “heterocyclic” includes both aromatic andnon-aromatic ring structures with one or more heteroatoms. Non-limitingexamples of heterocyclic includes, pyridine, isoquinoline, methylpyrroleand thiophene etc.

As briefly described above, the present invention is directed toplatinum and/or palladium complexes. In one aspect, the compositionsdisclosed here can provide emission spectra of platinum and/orpalladium. In another aspect, the compositions disclosed herein canprovide tunable emission spectra. In yet another aspect, thecompositions disclosed herein can have an emission spectrum having anarrow bandwidth.

In one aspect, the inventive composition comprises a platinum (II)complex. In another aspect, the inventive composition comprises apalladium (II) complex.

For any of the structures recited herein, unless specifically stated tothe contrary, various symbols and/or abbreviations are used wherein: Mrepresents platinum, palladium, or a combination thereof, where each ofAr₁, Ar₂, Ar₃, and Ar₄, if present, independently represent an aromaticring or heterocyclic group which can be substituted or unsubstituted;where each X_(n) can be coordinated to a platinum and/or palladium atom,and can independently represent a carbon and/or a nitrogen atom, whereinAr₅ can represent an aromatic ring, a heterocyclic group, or acombination thereof, where Ar₆ can represent an aromatic ring, aheterocyclic group, a combination thereof, or can be absent; where eachA_(n) can independently represent a linking atom, such as, for example,nitrogen, carbon, boron, phosphorus, silicon, or a combination thereof,and wherein each A_(n) can optionally be substituted, where each b_(n)can optionally be present or absent, and if present can independentlyrepresent oxygen, sulfur, nitrogen, carbon, boron, phosphorus, silicon,or a combination thereof.

Also, for any of the structures recited herein, R_(n) can representR₁-R₁₀, where each R can independently represent a hydrogen atom, analkyl group, a haloalkyl group, an aralkyl group, an alkenyl group, analkynyl group, an aryl group, an amino group, a mono- or di-alkylaminogroup, a mono- or diaryl amino group, an alkoxy group, an aryloxy group,a heteroaryloxy group, an alkoxycarbonyl group, an acyloxy group, anacylamino group, an alkoxycarbonylamino group, an aryloxycarbonylaminogroup, a sulfonylamino group, a sulfamoyl group, a carbamoyl group, analkylthio group, a sulfinyl group, an ureido group, a phosphoramidegroup, a hydroxyl group, amercapto group, a halogen atom, a cyano group,a sulfo group, a carboxyl group, a nitro group, a hydrzino group, asubstituted silyl group, a polymerizable group, or a combinationthereof; wherein if a plurality of R's are present (e.g., R_(n)), n canbe from about 0 to about 4, and wherein each R can be the same ordifferent from any other R, and wherein U, if present, can be oxygen,sulfur, or N—R_(n). Also, designation of R¹, R², R³ etc in theapplication relates to the definition of R_(n). Thus, limited subset ofR¹, R², R³ etc recited in the application does not preclude othersubstituents defined as R_(n) to also be included in that list.

In one aspect, the compositions of the present invention can berepresented by the general formula:

wherein M represents platinum, palladium, or a combination thereof,where each of Ar₁, Ar₂, and Ar₃ independently represent an aromatic ringor heterocyclic group which can be substituted or unsubstituted; whereineach of X₁, X₂ and X₃ can individually be coordinated to a platinumand/or palladium atom, and can independently represent a carbon or anitrogen atom, wherein Ar₅ can represent an aromatic ring, aheterocyclic group, or a combination thereof, where Ar₆ can represent anaromatic ring, a heterocyclic group, a combination thereof, or can beabsent; wherein W can be coordinated to a platinum or a palladium atom,and can be represented as a halogen atom, an aryl group, or a heteroarylgroup which may be substituted bonded directly or through an oxygenatom, sulfur atom, nitrogen atom, or phosphorous atom; wherein A canrepresent a linking atom, such as, for example, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof, and wherein A canoptionally be substituted, wherein each of b₁, b₂, and b₃ canindividually optionally be present or absent, and if present canindependently represent oxygen, sulfur, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof.

In one aspect, M can be Pt, such as Pt(II). In another aspect, M can bePd, such as Pd(II).

In one aspect, W can be Cl or F. For example, W can be Cl. In anotheraspect, W can be C₃-C₆ alkynyl. For example, W can be C₃ alkynyl. Inanother aspect, W can be nitrile. In another aspect, W can be C₆-C₁₀aryl. For example, W can be phenyl or naphthyl. The phenyl or naphthylcan be substituted or unsubstituted. For example, the phenyl can beunsubstituted. In another example, the phenyl can be alkyl substituted,such as C₁-C₆ alkyl substituted. In another aspect, the C₆-C₁₀ aryl canbe bonded to M via an oxygen atom. In another aspect, W can be C₅-C₉hetero aryl. For example, W can be isoquinoline. In another example, Wcan be quinazoline.

In one aspect,

can be pyridine, quinazoline, isoquinoline, methylimidazole, or

In one aspect,

can be phenyl or pyridine.

In one aspect,

can be phenyl or pyridine.

In one aspect,

can be phenyl.

In one aspect,

can be phenyl or can be absent. For example,

can be absent. In anther example,

can be phenyl.

In one aspect,

can be one or more of:

or a combination thereof. In one aspect, R^(n) can be C₁-C₃ alkyl. Forexample,

can be

In one aspect,

can be present or absent. For example,

can be absent. If present,

can, in one aspect, be —O—.

In one aspect,

can be present or absent. For example.

can be absent. In another example,

can be —S—, —S(R¹)₂—, —C(R²)₂—, —O—, —NH— or —NR^(n)—. In one aspect,each R¹ can individually be H or C₁-C₃ alkyl, for example C₂ alkyl. Inone aspect, each R² can individually be H or C₁-C₃ alkyl, for example C₁alkyl. In one aspect, R^(n) can be C₁-C₃ alkyl. For example, R^(n) canbe C₂ alkyl.

In one aspect,

can be present or absent. For example,

can be absent. In another example,

can be —S—, —S(R¹)₂—, —O—, —NH— or —NR^(n)—. In one aspect, each R¹ canindividually be H or C₁-C₃ alkyl, for example C₂ alkyl. In one aspect,R^(n) can be C₁-C₃ alkyl. For example, R^(n) can be C₂ alkyl.

In one aspect, W can be Cl, nitrile, phenyl, naphthyl or isoquinoline;and

can be isoquinoline, methylimidazole, or

In another aspect, W can be Cl, nitrile, phenyl, naphthyl orisoquinoline;

can be isoquinoline, methylimidazole, or

can be phenyl. In another aspect, W can be Cl, nitrile, phenyl, naphthylor isoquinoline;

can be isoquinoline, methylimidazole, or

can be phenyl; and

can be pyridine. In another aspect, W can be Cl, nitrile, phenyl,naphthyl or isoquinoline;

can be isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine;

can be phenyl; and

can be absent. In another aspect, W can be Cl, nitrile, phenyl, naphthylor isoquinoline;

can be isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine;

can be phenyl; and

can be phenyl.

In another aspect, the compositions of the present invention can berepresented by the general formula:

wherein M represents platinum, palladium, or a combination thereof,wherein each of Ar₁, Ar₂, Ar₃, and Ar₄ independently represent anaromatic ring or heterocyclic group which can be substituted orunsubstituted; where each of X₁, X₂, X₃ and X₄ can individually becoordinated to a platinum and/or palladium atom, and can independentlyrepresent a carbon and/or a nitrogen atom, wherein Ar₅ can represent anaromatic ring, a heterocyclic group, or a combination thereof, whereinAr₆ can represent an aromatic ring, a heterocyclic group, a combinationthereof, or can be absent; wherein each of A₁ and A₂ can independentlyrepresent a linking atom, such as, for example, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof, and wherein each of A₁and A₂ can independently optionally be substituted, wherein each of b₁and b₂ can individually optionally be present or absent, and if presentcan independently represent oxygen, sulfur, nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof.

In one aspect, M can be Pt, such as Pt(II). In another aspect, M can bePd, such as Pd(II).

In one aspect,

can be pyridine, quinazoline, isoquinoline, methylimidazole, or

In one aspect,

can be phenyl or pyridine.

In one aspect,

can be phenyl or pyridine.

In one aspect,

can be phenyl, pyridine, isoquinoline, naphthyl,

For example,

can be phenyl. In another example,

can be pyridine. In another example,

can be naphthyl or isoquinoline.

In one aspect,

can be phenyl.

In one aspect,

can be phenyl or absent. For example,

can be absent. In anther example,

can be phenyl.

In one aspect,

can be

or a combination thereof. In one aspect, R^(n) can be C₁-C₆ alkyl, suchas C₂ alkyl. For example,

can be

In one aspect,

can be

or a combination thereof. In one aspect, R^(n) can be C₁-C₆ alkyl, suchas C₂ alkyl. For example,

can be

In another aspect,

can be —O—, if

is absent.

In one aspect,

can be present or absent. For example,

can be absent. If present,

can be —O—.

In one aspect,

can be present or absent. For example,

can be absent. In another example,

can be —S—, —S(R¹)₂—, —C(R²)₂—, —O—, —NH— or —NR^(n)—. In one aspect,each R¹ can individually be H or C₁-C₃ alkyl, for example C₂ alkyl. Inone aspect, each R² can individually be H or C₁-C₃ alkyl, for example C₁alkyl. In one aspect, R^(n) can be C₁-C₃ alkyl. For example, R^(n) canbe C₂ alkyl.

In one aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl. In another aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl; and

can be pyridine. In another aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl; and

can be phenyl. In another aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine or phenyl;

can be phenyl; and

can be phenyl or pyridine. In another aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine or phenyl; and

can be phenyl or pyridine;

can be phenyl; and

can be absent. In another aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine or phenyl; and

can be phenyl or pyridine;

can be phenyl; and

can be phenyl.

In yet another aspect, the compositions of the present invention can berepresented by the general formula:

wherein M represents platinum, palladium, or a combination thereof,wherein each of Ar₁, Ar₂, Ar₃, and Ar₄ independently represent anaromatic ring or heterocyclic group which can be substituted orunsubstituted; wherein each of X₁, X₂, X₃ and X₄ can individually becoordinated to the platinum and/or palladium atom, and can independentlyrepresent a carbon and/or a nitrogen atom, wherein Ar₅ can represent anaromatic ring, a heterocyclic group, or a combination thereof, whereinAr₆ can represent an aromatic ring, a heterocyclic group, a combinationthereof, or can be absent; wherein A₁ can represent a linking atom, suchas, for example, nitrogen, carbon, boron, phosphorus, silicon, or acombination thereof, and wherein A₁ can optionally be substituted,wherein each b₁, b₂, and b₃ can individually optionally be present orabsent, and if present can independently represent oxygen, sulfur,nitrogen, carbon, boron, phosphorus, silicon, or a combination thereof.

In one aspect, M can be Pt, such as Pt(II). In another aspect, M can bePd, such as Pd(II).

In one aspect,

can be pyridine, quinazoline, isoquinoline, methylimidazole, or

In one aspect,

can be phenyl or pyridine.

In one aspect,

can be phenyl or pyridine.

In one aspect,

can be phenyl, pyridine, isoquinoline, naphthyl,

For example,

can be phenyl. In another example,

can be pyridine. In another example,

can be naphthyl or isoquinoline.

In one aspect,

can be phenyl.

In one aspect,

can be phenyl or absent. For example,

can be absent. In anther example,

can be phenyl.

In one aspect,

can be

or a combination thereof. In one aspect, R^(n) can be C₁-C₆ alkyl, suchas C₂ alkyl. For example,

can be

In one aspect,

can be present or absent. For example,

can be absent. If present,

can be —O—.

In one aspect,

can be present or absent. For example,

can be absent. In another example,

can be —S—, —S(R¹)₂—, —C(R²)₂—, —O—, —NH— or —NR^(n)—. In one aspect,each R¹ can individually be H or C₁-C₃ alkyl, for example C₂ alkyl. Inone aspect, each R² can individually be H or C₁-C₃ alkyl, for example C₁alkyl. In one aspect, R^(n) can be C₁-C₃ alkyl. For example, R^(n) canbe C₂ alkyl.

In one aspect,

can be

or a combination thereof. In one aspect, R^(n) can be C₁-C₆ alkyl, suchas C₂ alkyl. For example,

can be

In one aspect,

can be pyridine, isoquinoline, methylimidazole, or

can be phenyl. In another aspect,

can be isoquinoline, methylimidazole, or

can be phenyl; and

can be pyridine. In another aspect,

can be isoquinoline, methylimidazole, or

can be phenyl; and

can be phenyl. In another aspect,

can be isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine or phenyl; and

can be phenyl or pyridine. In another aspect,

can be isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine or phenyl; and

can be phenyl or pyridine; and

can be absent. In another aspect,

can be isoquinoline, methylimidazole, or

can be phenyl;

can be pyridine or phenyl; and

can be phenyl or pyridine; and

can be phenyl.

In one aspect, each of the above formulas

can comprise one or more of the following:

or a combination thereof. In one aspect, R¹ can be H or C₁-C₃ alkyl. Inone aspect, n can be 1 or 0. For example, n can be 0. In one aspect, R³can be C₁-C₃ alkyl. In one aspect, U can be —C(R²)₂, —O— or —S—. Each R²can individually be H or C₁-C₃ alkyl.

In another aspect, each of the above formulas

can each independently represent one or more of the following:

or a combination thereof.In one aspect, m can be 1 or 0. In one aspect, R² can be C₁-C₃ alkyl,for example C₂ alkyl.

In another aspect, in all above formulas each

can independently represent one or more of the following:

or a combination thereof. In one aspect, R^(n) can be C₁-C₃ alkyl, suchas C₂ alkyl.

In another aspect, in all above formulas each

can independently represent one or more of the following:

or a combination thereof. B_(n) is a generic description of B₁, B₂and/or B₃. In one aspect, R^(n) can be C₁-C₃ alkyl, such as C₂ alkyl.B_(n) can be present or absent.

In another aspect, in all above formulas

can represent one or more of the following:

or a combination thereof. In one aspect, b can —O—, —S—, —N(R′)—, or—C(R¹)₂—. In one aspect, each R¹ can individually be H or C₁-C₃ alkyl,such as C₂ alkyl. For example, b can be —O—, —S—, or —N(C₂H₅)—.

In another aspect, in all above formulas each of

each represent one or more of the following:

or a combination thereof. For example,

can individually be

In another aspect, in all above formulas

may be any one as following:

In one aspect, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰, canindividually be H or C₁-C₃ alkyl, such as C₂ alkyl. In one aspect, R¹,R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰, can individually be H. In oneaspect, U can be —C(R²)₂, —O— or —S—. Each R² can individually be H orC₁-C₃ alkyl.

In other aspects, the inventive composition can comprise any one or moreof the following specific examples:

or a combination thereof.

It should be understood that the specific exemplary compositions recitedherein are intended to be exemplary and not limiting. In another aspect,the present invention can exclude, or not include, any one or more ofthe compounds recited herein. For example, in one aspect, the presentinvention does not comprise the following complex:

The inventive compositions of the present disclosure can be useful in awide variety of applications, such as, for example, lighting devices. Ina particular aspect, one or more of the complexes can be useful as anemitter for an organic light emitting display device.

The compounds of the invention are useful in a variety of applications.As light emitting materials, the compounds can be useful in organiclight emitting diodes (OLEDs), luminescent devices and displays, andother light emitting devices, or as luminescent markers inbio-applications.

The emission (and absorption) profile of the compounds can be tuned byvarying the structure of the ligand surrounding the metal center. Forexample, compounds having a ligand with electron withdrawingsubstituents will generally exhibit different optical properties,including emission and absorption, than compounds having a ligand withelectron donating substituents. Generally, a chemical structural changeaffects the electronic structure of the compound, which thereby affectsthe absorption and emission of the compound. Thus, the compounds of thepresent invention can be tailored or tuned to a specific applicationthat desires a particular emission or absorption characteristic.

In another aspect, the emission spectrum of any of the compositions ofthe present disclosure can be tuned to a desired and/or customizedspectrum. In another aspect, the complexes disclosed herein can providea narrow bandwidth, enabling their use in, for example, applications inwhich broad spectrum emitters are not suitable.

In one aspect, the excited state dynamics of the complex can bedescribed by the scheme:

where ³LC represents the energy of the ligand centered triplet state,¹MLCT represents the energy of the metal-to-ligand charge transfersinglet state, T₁ represents the energy of the emissive triplet state,S₀ represents the energy of the ground state, and ΔE represents thedifference in energy between ¹MLCT and ³LC.

In still another aspect, an expansion utilizing different emittingportions and linking groups should provide narrow emitting complexescovering a wide range of the visible spectrum. The emission energy of acertain complex can be tuned by modifying the ligand centered tripletstate of the emitting fragment (³LC). This can be accomplished throughchanges in structure that modify the energy of the donating or acceptingportion of the emitting fragment.

In another aspect, the nature of the ¹MLCT transitions can be controlledby modifying the ancillary portion of the complex (L{circumflex over( )}X), through changes in the cyclometalating portion, the linkingportions, or both.

In one aspect, the inventive compositions are useful as emitters forfull color display application. In such an aspect, the geometry ofcyclometalating ligands can be rigid. This rigidity can allow forsimilar geometry between the ground and excited state, resulting in anarrow emission spectra dominated by the transition from the lowestvibrational level in the excited state to the lowest vibrational levelin the ground state.

In another aspect, complexes can be designed to tune the values of theemitting fragment centered ³LC state and the metal to ancillary ligand¹MLCT states independently. Reduction in the differences in energybetween these states (ΔE) will improve mixing between them, improve theradiative decay rate, and suppress transitions that occur from theemissive state (T₁) to excited vibrational levels in the ground state(S₀). As a consequence, the vibrational shoulders of the emissionspectra can be reduced, resulting in a more narrow emission profile.

In a further aspect, the molecular structure having four coordinatingligands to a metal center can be preferred. In such an aspect, a fourligand coordinated structure can at least partially ensure theelectrochemical and/or photophysical stability of the complex during,for example, fabrication and operation of a color display device.

In another aspect, the inventive compositions can provide improvedefficiency and/or operational lifetimes in lighting devices, such as,for example, organic light emitting devices, such as OLEDs, as comparedto conventional materials. Thus, also disclosed herein are devicescomprising the complexes described herein. One application forphosphorescent emissive complexes, such as those described herein, is afull color display. Industry standards for such a display call forpixels adapted to emit particular colors, referred to as “saturated”colors. In particular, these standards call for saturated red, green,and blue pixels. Color may be measured using CIE coordinates, which arewell known to the art.

In other various aspects, the inventive compositions can be useful as,for example, luminescent labels, emitters for organic light emittingdiodes, lighting applications, and combinations thereof.

The compounds of the invention can be made using a variety of methods,including, but not limited to those recited in the examples providedherein. In other aspects, one of skill in the art, in possession of thisdisclosure, could readily determine an appropriate method for thepreparation of an iridium complex as recited herein.

EXAMPLES

The following examples are put forth so as to provide those of ordinaryskill in the art with a complete disclosure and description of how thecompounds, compositions, articles, devices and/or methods claimed hereinare made and evaluated, and are intended to be purely exemplary of theinvention and are not intended to limit the scope of what the inventorsregard as their invention. Efforts have been made to ensure accuracywith respect to numbers (e.g., amounts, temperature, etc.), but someerrors and deviations should be accounted for. Unless indicatedotherwise, parts are parts by weight, temperature is in ° C. or is atambient temperature, and pressure is at or near atmospheric.

Example 1

4′-bromo-2-nitrobiphenyl: Under a nitrogen atmosphere, 20 mL of waterwas heated to 60° C. and 125 mmol of 2-nitrobyphenyl was added andstirred for 30 minutes before 6.3 mmol of iron trichloride was added andstirred for 30 minutes further. 140 mmol of bromine was added dropwiseover 40 minutes and allowed to stir overnight before setting to refluxfor 4 hours. After cooling, residual bromine was removed by washing witha sodium bisulfate solution. The organic residue was then washed twicewith water, twice with concentrated sodium hydroxide, and then twicewith water. The organic portion was separated and dissolved indichloromethane before being dried with magnesium sulfate. The solutionwas concentrated under reduced pressure, subjected to flash columnchromatography of silica with dichloromethane as the eluent, andconcentrated again under reduced pressure. 4′-bromo-2-nitrobiphenyl wascollected by recrystallization from methanol in 50% yield.

2-bromo-9H-carbazole: Under a nitrogen atmosphere, 100 mmol of4′-bromo-2-nitrobiphenyl was set to reflux overnight in stirringtirethylphosphite. After cooling, the triethylphosphite was distilledoff and 2-bromo-9H-carbazole was isolated by recrystallization frommethanol and further purified by train sublimation, resulting in a 65%yield.

2-bromo-9-(pyridin-2-yl)-9H-carbazole: Under a nitrogen atmosphere, 10mmol of 2-bromo-9H-carbazole, 15 mmol of 2-bromopyridine, 1 mmol ofcopper(I)iodide, 25 mmol of potassium carbonate, and 2 mmol of L-prolinewere combined in stirring degassed dimethyl sulfoxide. The mixture washeated to 90° C. for 3 days before being cooled and separated betweendichloromethane and water. The water layer was washed twice withdichloromethane and the organics were combined and washed once withbrine. The organic fraction was dried with magnesium sulfate andconcentrated under reduced pressure and subjected to columnchromatography of silica with dichloromethane as the eluent. Afterconcentrating under reduced pressure,2-bromo-9-(pyridin-2-yl)-9H-carbazole was isolated in a 70% yield.

2-bromo-9-(tetrahydro-2H-pyran-2-yl)-9H-carbazole: 10 mmol of2-bromo-9H-carbazole, 0.1 mmol of pyridinium toluene-4-sulphonate, and50 mmol of 3,4-dihydro-2H-pyran was added to dichloromethane at roomtemperature and let stir for 2 hours before the temperature was raisedto 50° C. for 2 hours further. The solution was cooled, concentratedunder reduced pressure, and subjected to column chromatography of silicawith dichloromethane as the eluent. After concentrating under reducedpressure, 2-bromo-9-(tetrahydro-2H-pyran-2-yl)-9H-carbazole was isolatedin 90% yield.

2-(1H-pyrazol-1-yl)-9-(tetrahydro-2H-pyran-2-yl)-9H-carbazole: Under anitrogen atmosphere, 10 mmol of2-bromo-9-(tetrahydro-2H-pyran-2-yl)-9H-carbazole, 15 mmol of pyrazole,1 mmol of copper(I)iodide, 25 mmol of potassium carbonate, and 2 mmol ofL-proline were combined in 25 mL of stirring degassed dimethylsulfoxide. The mixture was heated to 90° C. for 3 days before beingcooled and separated between dichloromethane and water. The water layerwas washed twice with dichloromethane and the organics were combined andwashed once with brine. The organic fraction was dried with magnesiumsulfate and concentrated under reduced pressure and subjected to columnchromatography of silica with dichloromethane as the eluent. Afterconcentrating under reduced pressure,2-(1H-pyrazol-1-yl)-9-(tetrahydro-2H-pyran-2-yl)-9H-carbazole wasisolated in a 40% yield.

2-(1H-pyrazol-1-yl)-9H-carbazole: 5 mmol of2-(1H-pyrazol-1-yl)-9-(tetrahydro-2H-pyran-2-yl)-9H-carbazole wasdissolved in 100 mL of methanol before 25 mmol of methylsulfonic acidwas added slowly. The solution was stirred at room temperature for 2hours, then at 50° C. for 2 hours further. The reaction was cooled,quenched with sodium bicarbonate, and separated between dichloromethaneand water. The water was washed twice with dichloromethane, the organicfractions combined and washed once with brine. The organic fraction wasthen dried with magnesium sulfate, filtered, and the filtrateconcentrated under reduced pressure. The resulting solid was subjectedto column chromatography, using silica and dichloromethane/ethyl acetateas the eluent. After concentration under reduced pressure,2-(1H-pyrazol-1-yl)-9H-carbazole was isolated in 90% yield.

2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole: Under anitrogen atmosphere, 10 mmol of 2-(1H-pyrazol-1-yl)-9H-carbazole, 10mmol of 2-bromo-9-(pyridin-2-yl)-9H-carbazole, 1 mmol ofcopper(I)iodide, 25 mmol of potassium carbonate, and 2 mmol of L-prolinewere combined in stirring degassed dimethyl sulfoxide. The mixture washeated to 90° C. for 3 days before being cooled and separated betweendichloromethane and water. The water layer was washed twice withdichloromethane and the organics were combined and washed once withbrine. The organic fraction was dried with magnesium sulfate andconcentrated under reduced pressure and subjected to columnchromatography of silica with dichloromethane/ethyl acetate as theeluent. After concentrating under reduced pressure,2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole was isolatedin a 60% yield.

[2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole]Pt(II),PtN1N: Under a nitrogen atmosphere, 10 mmol of2′-(1H-pyrazol-1-yl)-9-(pyridin-2-yl)-9H-2,9′-bicarbazole, 9 mmol ofK₂PtCl₄, and 4 Å molecular sieves were added to stirring acetic acid.The mixture was heated to 120° C. for 3 days. The solution was cooled,and poured into 100 mL of stirring dichloromethane. The mixture wasfiltered, and the filtrate concentrated under reduced pressure. Theemissive solid was subjected to flash chromatography of silica withdichloromethane as the eluent.

1.-23. (canceled)
 24. A composition represented by the general formula:

wherein M is platinum or palladium; each of Ar₁, Ar₂, and Ar₃independently is an aromatic ring or heterocyclic group which can besubstituted or unsubstituted; each of X₁, X₂ and X₃ are individuallycoordinated to a platinum or palladium atom, and independently is acarbon or a nitrogen atom; Ar₅ is an aromatic ring or a heterocyclicgroup; Ar₆ is an aromatic ring, a heterocyclic group, or is absent; W iscoordinated to the platinum or a palladium atom, and is a halogen atom,a nitrile group, an aryl group, a C₃-C₆ alkynyl group, an alkenyl group,or a heteroaryl group; wherein W is optionally bonded directly orthrough an oxygen atom, sulfur atom, nitrogen atom, or phosphorous atom;A represents a linking atom comprising nitrogen, carbon, boron,phosphorus, silicon, or a combination thereof, and wherein A isoptionally substituted; each of b₁, b₂. and b₃ is individuallyoptionally present or absent, and if present comprises oxygen, sulfur,nitrogen, carbon, boron, phosphorus, silicon, or a combination thereof.25. The composition of claim 24, wherein

represents one of the following structures:

wherein U is —C(R²)₂, —O— or —S—; n is 1 or 0; each R¹ and R² is eachindependently H or C₁-C₃ alkyl; and R³ is C₁-C₃ alkyl.
 26. Thecomposition of claim 24, wherein

each independently represent one of the following structures:

or a combination thereof; wherein m is 1 or 0; and R² is C₁-C₃ alkyl.27. The composition of claim 24, wherein each of

independently represent one of the following structures:


28. The composition of claim 24, wherein

is represented by one of the following structures:

wherein U is —C(R²)₂, —O— or —S—; and each occurrence of R¹, R², R³, R⁴,R⁵, R⁶, R⁷, R⁸, R⁹, and R¹⁰ is independently H or C₁-C₃ alkyl.
 29. Thecomposition of claim 24, wherein W is Cl, F, C₃ alkynyl, nitrile,quinazoline, isoquinoline, substituted or unsubstituted phenyl, orsubstituted or unsubstituted naphthyl.
 30. The composition of claim 24,wherein

is pyridine, quinazoline, isoquinoline, methylimidazole, or


31. The composition of claim 24, wherein

is phenyl or pyridine.
 32. The composition of claim 24, wherein

is phenyl or pyridine.
 33. The composition of claim 24, wherein

is absent.
 34. The composition of claim 24, wherein W is Cl, nitrile,phenyl, naphthyl or isoquinoline;

is isoquinoline, methylimidazole, or

is phenyl;

is pyridine; and

is phenyl.
 35. The composition of claim 24, wherein

represents

or a combination thereof; wherein R^(n) is C₁-C₃ alkyl.
 36. Thecomposition of claim 24, wherein b₁ is absent.
 37. The composition ofclaim 24, wherein b₂ is —S—, —S(R¹)₂—, —C(R²)₂—, —O—, —NH— or —NR^(n)—;wherein each R¹ and R² is independently H or C₁-C₃ alkyl; and R^(n) isC₁-C₃ alkyl.
 38. The composition of claim 24, wherein M comprisesplatinum(II).
 39. The composition of claim 24, wherein M comprisespalladium(II).
 40. The composition of claim 24, comprising

or a mixture thereof.
 41. An organic light emitting device (OLED)comprising the compound of claim
 24. 42. A full color display comprisingthe OLED of claim 41.